1. Field of the Invention
This invention pertains to a system for raising or lowering chandeliers, more specifically to an electrically operated system which unfalteringly moves the chandelier to, and retains the chandelier safely at, any height within a predetermined range.
2. Description of the Prior Art
There are a multitude of chandelier lift apparatus patented designs of various complexities and cost, for raising and lowering chandeliers with ease and safety. U.S. Pat. No. 3,610,584 patented Oct. 5, 1971, by H. C. Pfaff, Jr., describes a device having an upper section mounted to the ceiling, the device includes an electric motor having a vertical drive shaft, the lower portion of which is adapted for chain driving a vertical worm gear shaft.
The worm gear drives upon the periphery of a drum upon which is wound a flat ribbon. One end of the ribbon extends downward from the drum, and is attached to the electrical fixture for raising or lowering of the fixture by rotation of the drum.
The upper portion of the drive shaft above the motor has a brake disk. Brake jaws are spring-biased to clamp on the brake disk unless opened by a first electric solenoid.
In order to raise or lower the fixture, electrical power is applied to the solenoid and the motor so that the brake is released while the motor is driving.
A spring-biased latching mechanism on the upper section of the device moves a hook into engagement with a U-bolt on the lower section of the device when the lower section is lifted fully to the upper section. This prevents the fixture from falling should the brake fail after the fixture is fully lifted. A second electrical solenoid is attached to the hook to withdraw it from the U-bolt when electrical power is applied to the motor and first solenoid, in order to raise or lower the fixture.
U.S. Pat. No. 4,316,238, patented Feb. 16, 1982, by Booty et al. describes an apparatus for raising and lowering a light fixture with respect to a ceiling in which the frame of the apparatus is mounted.
The frame has a spring wound around a shaft and attached by one end to a carriage which is mounted on the frame for horizontal movement, so that the spring biases the carriage toward the shaft.
A combination electrical and support cable is attached by one end to the frame. Extending horizontally, the cable passes around a first pulley on the carriage, loops back horizontally, passes over a second pulley that is mounted on the frame, and suspends below the frame, a light fixture to which the cable is attached.
The carriage, being biased by the spring toward the shaft upon which the spring is wound, is pulled away from the shaft by the cable drawing upon the first pulley as the fixture is drawn down and the length of the horizontal cable loop decreases.
A horizontal piston is attached at one end to the carriage so that it is moved horizontally by the moving carriage. In one embodiment, the other end of the piston is connected to a dashpot to control the rate of descent of the fixture. The spring is designed to partially counterbalance the weight of the fixture so that the fixture falls of its own weight.
A second cable passing over a pulley which is coaxial with the spring shaft is attached at one end to the carriage and has a knob at the other end for grasping and pulling down to draw the fixture back up by drawing the carriage toward the spring shaft. A bead on the second cable engages a catch on the frame when the knob is drawn down far enough to bring the light fixture to the uppermost position. The bead and catch keep the light fixture from moving down until, to lower the fixture, the second cable is pulled laterally until the bead escapes the catch, allowing the second cable and knob to raise up.
In another embodiment, there is no second cable, and no dashpot. The fixture weighs less than the bias force from the spring and does not fall of its own accord but has a finger loop by which it can be drawn down against the bias of the spring.
A transverse pin through the piston engages a clip when the piston is moved horizontally away from the spring shaft by the carriage as the fixture moves to the lowered position. The clip prevents the fixture from moving back up, but it can be disengaged by pulling the fixture further down a bit. Freeing the piston allows the carriage to move toward the spring shaft and the fixture to move toward the ceiling.
In another embodiment, instead of a dashpot on the piston to control the rate of descent of the fixture, a frictional drag mechanism is incorporated on the spring shaft.
A motorized chandelier lift system for raising and lowering a light fixture between a raised position adjacent to a ceiling and a lowered position distant from the ceiling, described in U.S. Pat. No. 5,105,349, patented Apr. 14, 1992, by Falls et al., has a hoist mechanism mounted above the ceiling from which the chandelier hangs. The hoist mechanism includes a drive motor having a drive shaft and a take-up shaft directly coupled to the drive shaft. A single hoist cable is attached at one end to the take up shaft for being wound on the take up shaft, and at the other end to a junction box on the light fixture. A junction box on the ceiling includes a set of contacts for supplying electrical power to the light fixture. The junction box on the light fixture includes a set of electrical contacts for receiving electricity from the ceiling junction box by contacting the electrical contacts in the ceiling junction box when the fixture is in the second position.
The light fixture is raised and lowered by winding and unwinding the hoist cable on the take-up shaft. The motor or the cable winder portion of the hoist mechanism may include a self-activating automatic brake.